Various means for marking and identifying items in hidden ways is discussed in U.S. Pat. No. 4,767,205, the teachings of which are incorporated herein by reference.
Microbeads, which are spherical particles, consisting of polymeric materials of specific sizes and color or fluorescence have been used singly or in combinations to provide unique codes which are defined by the sizes and colors of the microbeads as more fully described in the referred to U.S. Pat. No. 4,767,205, this patent also describes use of microbeads in epoxy media to mark equipment and in paper or inks to mark printed materials such as documents, stamps, money and lottery tickets. This patent further identifies other patents and information, all deemed incorporated herein by reference, which teach methods of making microbeads with sufficient uniformity of shape, color and size as to be suitable for the present invention.
Fluorescent dyes have specific properties which are related to their appearance with respect to the wavelength of light with which they are excited and the barrier filters with which they are viewed. The manner in which fluorescent dyes may provide codings equivalent to specific colors is also more fully described in the previously mentioned U.S. Pat. No. 4,767,205.
However, what has not heretofore been recognized is the possibility of creating a coded identification on a multiplicity of documents or other items by incorporating the coding composition mixed in with a composition like that found in a toner cartridge such that the coding can be carried out automatically, for example, as part of a photocopy or laser printing operation.
Toner cartridges such as used in photocopy machines and laser printers generally contain a composition of particles hereafter referred to as "toner particles". The XEROX.TM. dry ink cartridge 5012/5014/1012 is advertised as comprising Styrene Acrylate Polymer; Iron Oxide; Polypropylene Blue Wax; Quaternary Ammonium Salt; and Amorphous Silica. The toner particles are attracted to drums which have electrostatic patterns placed on them to match the print or copy patterns desired. These particles are non-fluorescent and provide a black background when viewed by eye or under a microscope.
The object of the invention thus becomes that of providing a coding composition, method and apparatus for creating a hidden identification based on incorporating the coding composition with another printing composition confined in a container such as a toner cartridge such that the coding can be applied while other printing or copying processes take place.
A more specific object is to provide a toner cartridge composition suited for a normal printing purpose as well as for use in applying a hidden identification that can later be detected making use of fluorescent or other properties of the coding composition.
Other objects will become apparent as the description proceeds.